Hydrogen formation in the reaction of Zn+ (H2O)n with HCl.

Hydrated singly charged zinc cations Zn (H2O)n, n approximately 6-53, were studied by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Black-body radiation induced dissociation results exclusively in sequential loss of individual water molecules. In the reaction of Zn+ (H2O)n with gaseous HCl, Zn is oxidized and hydrogen reduced when a second HCl molecule is taken up, leading to the formation of ZnCl+ (HCl)(H2O)n-m cluster ions and evaporation of atomic hydrogen together with m H2O molecules. The results are compared with earlier studies of Mg+ (H2O)n, for which hydrogen formation is already observed without HCl in a characteristic size region. The difference between zinc and magnesium is rationalized with the help of density functional theory calculations, which indicate a distinct difference in the thermochemistry of the reactions involved. The generally accepted hydrated electron model for hydrogen formation in Mg+ (H2O)n is modified for zinc to account for the different reactivity.

Reactions of hydrated electrons (H2O)n- with carbon dioxide and molecular oxygen: hydration of the CO2- and O2- ions.

The gas-phase reactions of hydrated electrons with carbon dioxide and molecular oxygen were studied by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Both CO2 and O2 react efficiently with (H2O)n- because they possess low-lying empty pi* orbitals. The molecular CO2- and O2- anions are concurrently solvated and stabilized by the water ligands to form CO2(-)(H2O)n and O2(-)(H2O)n. Core exchange reactions are also observed, in which CO2(-)(H2O)n is transformed into O2(-)(H2O)n upon collision with O2. This is in agreement with the prediction based on density functional theory calculations that O2(-)(H2O)n clusters are thermodynamically favored with respect to CO2(-)(H2O)n. Electron detachment from the product species is only observed for CO2(-)(H2O)2, in agreement with the calculated electron affinities and solvation energies.

Generation of C6H4+* by laser vaporization of magnesium with o-C6H4F2 in argon carrier gas.

A route to efficient generation of C6H4+*, potentially the benzyne radical cation, is presented. Laser vaporization of Mg+* and supersonic expansion in helium doped with o-, m-, or p-C6H4F2 yields, among other ions, o-, m-, p-C6H4F2Mg+* complexes, but no C6H4+*. Collision-induced dissociation experiments show that the o-C6H4F2Mg+* complex can be converted into C6H4+* in a mildly energetic collision, with a center-of-mass energy around 1-2 eV. These conditions can also be reached in the ion source when argon is used as a carrier gas. In this way, mass spectra containing the desired m/z 76 peak, i.e. C6H4+*, are obtained.

Aqueous chemistry of transition metals in oxidation state (I) in Nanodroplets.

"Nanodroplets" consisting of a central ion surrounded by a solvation shell of water molecules provide an interesting medium for studies of aqueous transition-metal chemistry in the unusual oxidation state (I). While VI undergoes efficient, solvent shell dependent redox reactions to VII and VIII, the absence of any similar reactivity in aqueous CrI, Mn1, FeI, CoI, NiI, and CuI clusters is explained by a rapid precipitation of the corresponding single monochloride molecules from the nanosolutions.

Single-molecule precipitation of transition metal(I) chlorides in water clusters.

Metal ions in unusual oxidation states can be introduced into water clusters using a standard laser vaporization source. Such nanosolutions of a single ion in typically 50 water molecules are comparable to a 1 M bulk solution, and their chemistry can be studied in the ion trap of a Fourier transform ion cyclotron resonance mass spectrometer. We find that a strong acid like hydrogen chloride oxidizes the early transition metal vanadium to the more common +III state, while later first row transition metals retain their unusual +I oxidation state, and the binary metal chlorides M(I)Cl precipitate.